Prior to the invention of the class of binders including this invention, the state-of-the-art in solid propellants for man-rated or Department of Defense (DoD) class 1.3 (non mass-detonable) applications were those containing an inert hydroxy-terminated polybutadiene (HTPB) binder. These formulations generally contain 86 to 88% solids and use ammonium perchlorate oxidizer. They may also use an inert plasticizer such as dioctyl sebacate (DOS) or dioctyl adipate (DOA), aluminum fuel, and solid cyclic nitfamines cyclotetramethylene tetranitramine (HMX) or cyclotrimethylene trinitramine (RDX). The HTPB propellants are useful because they are less expensive and safer to use than double-base propellants which are DoD class 1.1 (mass-detonable).
HTPB propellants also have low electrical conductivities (or high resistivities) which makes them susceptible to catastrophic dielectric breakdown and other electrostatic hazards. Electrostatic discharge is known to have been the cause of disastrous fires which have occurred during the handling and manufacture of prior art rocket motors containing HTPB bound propellant.
HTPB propellants require high depressurization rates to extinguish. Consequently, they are not suitable for use in applications where thrust termination through rapid motor depressurization is required.
The instant inventors have developed a new class of propellants having binders made with non-crystalline polyethers which have improved safety (electrical conductivity), performance (density), and ballistics (extinguishment), as compared to the HTPB based propellants. One such propellant has a binder system comprising a non-crystalline polyether and an energetic plasticizer. The instant inventors have developed a propellant having similar performance features to those of that invention but which is safer, e.g., has even greater extinguishment, particularly during depressurization.